Growth of highly c-axis oriented Mg:ZnO nanorods on Al_2O_3 substrate towards high-performance H_2 sensing

摘要

Highly c-axis oriented Mg:ZnO films were fabricated on Al_2O_3 substrate by radio frequency sputtering for different substrate temperatures. The crystal structure revealed that the Mg dopants are well integrated into ZnO wurtzite lattice. X-ray photoelectron spectroscopy measurements also confirmed the successful incorporation of Mg into ZnO. The substrate temperature exhibit significant influence on the optical absorbance and band gap of Mg:ZnO films. Scanning electron microscope images revealed the formation of Mg:ZnO nanorods with good crystalline quality. The films prepared at 1200 ℃ show well grown rods of Mg:ZnO due to strengthening of the preferred orientation of ZnO along the c-axis. The Mg:ZnO/Al_2O_3 films prepared at different temperature were tested for its sensing performance towards 200 ppm of H_2 at room temperature. The Mg:ZnO sensor prepared at 1200 ℃ revealed fast response and recovery time of about 85 s and 70 s, respectively. The response of the sensor was linear to H_2 concentration in the range of 100-500 ppm. It can be summarized that this high performance H_2 sensor has potential for use as a portable room temperature gas sensor.